Magnetic media are used in the form of tapes, floppy disks, hard disks, and the like to store magnetic impulses received from a recording or write head scanned on the medium and to reconstruct the same impulses in a playback or read head scanned on the same part of the medium. The write and read functions of a computer disk system are commonly performed by a single read/write head. The head moves rapidly with respect to the magnetic medium and closely approaches it, momentarily coming into direct contact with it when the head starts or stops scanning. The industry has found it necessary to lubricate the magnetic medium so friction between the medium and head does not rapidly destroy the head or the medium.
Computer data storage media such as oxide disks have been coated with a 30 to 120 Angstrom layer of fluorinated oil to reduce friction while the head is in contact with the disk, and to protect the disk from corrosive atmospheric contaminants. This coating has worked well for systems achieving densities of no more than about 60 to 100 megabytes per square inch, wherein the read/write heads fly relatively high over the recording medium, riding on an air cushion. Other materials which have found utility as lubricants for magnetic media used with high-flying read-write heads include fluorinated oils (particularly perfluoropolyethers), fatty acids and their esters, organosilanes, and organoaminosilanes.
In higher-density magnetic storage systems currently under development, the read/write heads will fly lower. The lubricant layer for such heads will typically be much thinner--perhaps less than 30 Angstroms thick. Such a thin layer of a conventional lubricant will not lubricate the magnetic medium sufficiently to allow it to withstand the increased friction resulting from repeated scanning by low-flying heads.
Another problem in the art is degradation of the lubricant. Fatty aliphatic chains (broadly defined herein as those having from 6 to 22 carbon atoms) degrade with each read/write cycle, forming a buildup of sludge. This sludge causes higher friction between the magnetic medium and the head, head instability, and increased spacing between the head and the medium surface. Deterioration of performance is the practical result.
Thus, a need has arisen for new lubricants which will durably adhere to the disk in thin layers, will allow repeated read/write cycles without an increase in friction or sludge buildup, will offer corrosion protection, and will provide better lubrication in the environment of a low flying read/write head.